Cryogenic Missions Research Articles

Development of an apparatus and process for precision measurements of cryogenic thermal contraction of materials

NASA frequently needs thermal contraction data for materials to be used in cryogenic space flight missions. To satisfy this need, we developed an apparatus and a high-precision technique for performing such measurements using a commercial fiber-optic-based position sensor. We describe the measurement process and its verification using a copper sample. We also present data for alumina and sintered samarium cobalt, which we characterized for potential NASA use.

Spitzer Publication Statistics

We present statistics on the number of refereed astronomy journal articles that used data from NASA’s Spitzer Space Telescope through the end of the calendar year 2020. We discuss the various types of science programs and science categories that were used to collect data during the mission and discuss how operational changes brought on by the depletion of cryogen in 2009 May, including the resulting budget cuts, impacted the publication rate. The post-cryogenic (warm) mission produced fewer papers than the cryogenic mission, but the percentage of the exposure time published did not appreciably change between the warm and cryogenic missions. This was mostly because in the warm mission the length of observations increased, so that each warm paper on average uses more data than the cryogenic papers. We also discuss the speed of publication, archival usage, and the tremendous efficacy of the Legacy and Exploration Science programs (large, coherent investigations), including the value of having well-advertised enhanced data products hosted in centralized archives. We also identify the observations that have been published the largest number of times, and sort them by a variety of metrics (including program type, instrument used, and observation length). Data that have the highest reuse rates in publications were taken early in the Spitzer mission, or belong to one of the large surveys (large either in number of objects, in number of hours observed, or in area covered on the sky). We also assess how often authors have cited the Spitzer fundamental papers or have correctly referenced the Spitzer data they used, finding that as many as 40% of papers have failed to cite the papers, and 15% have made it impossible to identify the data they used.

Thermal Property Measurements of Al-Alloy for Space Cryogenic Missions

In space cryogenic missions, the thermophysical properties of materials must be studied and measured to establish a highly reliable cooling chain. An Al-alloy is a primary material in cryogenic thermal structural designs and is particularly used for providing high thermal conductance of thermal shields and thermal straps. We measured low-temperature properties (the thermal conductivity and the electrical resistivity) of several Al-alloys and found that A6063 had a lower thermal conductivity than that reported previously. We also found that the Al-alloy ST-60, which has equivalent thermal conductivity as pure aluminum, has higher thermal conductivity than A6061 and A6063, and the material is a good candidate for the space cryogenic design at the temperature range between 4K and 300K. These results are critical for the thermal study of upcoming next-generation space astronomy missions, such as LiteBIRD, SPICA and ATHENA.

Outgassing of Three Space Materials from to 25°C

Cryogenic space-science missions have been expanding in the last few years. Onboard instruments, especially detectors, but also several parts of satellites can be cooled down to cryogenic temperature during cruise, commissioning phase and in operation. In such conditions, molecular contamination may happen and affect the performance of sensitive equipment. Polymer outgassing is the main source of contaminants, and this phenomenon is commonly studied from ambient temperature to high temperature, usually . However, very few experimental data exist and there is no real evidence that tends to confirm that outgassing is negligible at temperature below . This work aimed at studying the outgassing of some representative materials such as multilayer insulation and adhesives at low temperature. A multistep temperature profile from to has been applied to the materials and deposition kinetics measured using cryogenic quartz crystal microbalance. The results showed different interesting behaviors and highlighted outgassing beginning at . Based on these results, long-term predictions have been calculated with internal simulation tool. Moreover, in situ analysis of outgassed molecules has been attempted with a residual gas analyzer.

Cryogenic radiator with cavity-in-cavity structure for space missions

A new cryogenic radiator with high emissivity under 50K has been designed, fabricated and tested for space cryogenic missions in which high emissivity radiative cooling at low temperature is proposed. In this design, a cavity is introduced in a cavity surface structure to make a low reflectivity surface at an infrared wavelength (ranging from a few tens of μm up to 1000 μm) without any black coating resulting in contamination and low reliability at low temperature. As proof of a concept demonstration, a triple-cavity surface structure was designed, and three types of test pieces with different number of surface cavities were measured. Low temperature emissivity measurement using the calorimetric method, revealed that higher emissivity was successfully obtained with the test piece having a higher number of cavities.

SPICA/BLISS cryo-chain demonstrator

The Background Limited Infrared Submillimeter Spectrometer (BLISS) is an instrument proposed for SPICA, the Japanese–European space-borne telescope mission under study for a possible launch in the next decade. The BLISS concept is a suite of aluminum spectrometer modules totaling ∼10kg cooled to 50mK. Cooling this ambitious instrument with high-duty cycle within the stringent heat-rejection allocations envisioned for SPICA is a challenge. We have developed a solution consisting of two stages: (1) a continuous 300mK intercept stage provided by two 3He sorption coolers operated sequentially, and (2) a 50mK adiabatic demagnetization refrigerator (ADR) operated in single-shot mode. We have built a prototype cooler and demonstrated it in a dedicated SPICA-like thermal testbed with regulated stages enabling measurement of rejected heat at 1.7K and 4.5K. The approach offers lower mass than a dual-stage ADR, and lower rejected power to 1.7K and 4.5K than a comparable single-shot 300mK system, while insuring a high duty cycle. As a demonstration of feasibility for SPICA and future cryogenic missions, we show long-term cooling with flight-like parasitics at 50mK and 300mK requiring only 3mW and 8mW rejected at 1.7K and 4.5K, respectively.

Design, fabrication and test of Load Bearing multilayer insulation to support a broad area cooled shield

Improvements in cryogenic propellant storage are needed to achieve reduced or Zero Boil Off of cryopropellants, critical for long duration missions. Techniques for reducing heat leak into cryotanks include using passive multi-layer insulation (MLI) and vapor cooled or actively cooled thermal shields. Large scale shields cannot be supported by tank structural supports without heat leak through the supports. Traditional MLI also cannot support shield structural loads, and separate shield support mechanisms add significant heat leak. Quest Thermal Group and Ball Aerospace, with NASA SBIR support, have developed a novel Load Bearing multi-layer insulation (LBMLI) capable of self-supporting thermal shields and providing high thermal performance.We report on the development of LBMLI, including design, modeling and analysis, structural testing via vibe and acoustic loading, calorimeter thermal testing, and Reduced Boil-Off (RBO) testing on NASA large scale cryotanks.LBMLI uses the strength of discrete polymer spacers to control interlayer spacing and support the external load of an actively cooled shield and external MLI. Structural testing at NASA Marshall was performed to beyond maximum launch profiles without failure. LBMLI coupons were thermally tested on calorimeters, with superior performance to traditional MLI on a per layer basis. Thermal and structural tests were performed with LBMLI supporting an actively cooled shield, and comparisons are made to the performance of traditional MLI and thermal shield supports. LBMLI provided a 51% reduction in heat leak per layer over a previously tested traditional MLI with tank standoffs, a 38% reduction in mass, and was advanced to TRL5. Active thermal control using LBMLI and a broad area cooled shield offers significant advantages in total system heat flux, mass and structural robustness for future Reduced Boil-Off and Zero Boil-Off cryogenic missions with durations over a few weeks.

Planckearly results. II. The thermal performance ofPlanck

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20K for LFI and 0.1K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20K), a 4He Joule-Thomson cooler (4.7K), and a 3He-4He dilution cooler (1.4K and 0.1K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, andoperates at a mean temperature of 384K. At the other end of the spacecraft, the telescope baffle operates at 42.3K and the telescope primary mirror operates at 35.9K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

Theoretical noise analysis on a position-sensitiveMetallic Magnetic Calorimeter

We report on the theoretical noise analysis for a position-sensitive MetallicMagnetic Calorimter (MMC), consisting of MMC read-out at both ends of a large X-rayabsorber. Such devices are under consideration as alternatives to other cryogenic technologiesfor future X-ray astronomy missions. We use a finite-element model (FEM) to numericallycalculate the signal and noise response at the detector outputs and investigate the correlationsbetween the noise measured at each MMC coupled by the absorber. We then calculate, using theoptimal filter concept, the theoretical energy and position resolution across the detector anddiscuss the trade-offs involved in optimising the detector design for energy resolution, positionresolution and count rate. The results show, theoretically, the position-sensitive MMC conceptoffers impressive spectral and spatial resolving capabilities compared to pixel arrays and similarposition-sensitive cryogenic technologies using Transition Edge Sensor (TES) read-out.

Assessment of electronics for cryogenic space exploration missions

Space exploration missions require electronics capable of efficient and reliable operation at low temperatures. Presently, spacecraft on-board electronics are maintained at approximately 20 °C through the use of radioisotopes. Cryogenic electronics would enhance efficiency of space systems, improve reliability, and simplify their design. A Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electronics suitable for space exploration missions. The effects of cryogenic temperature and thermal cycling are being investigated for commercial-off-the-shelf components as well as for components specially developed for low temperature operation. An overview of this program along with selected experimental data is presented in this paper.

Payload and spacecraft technology for GP-B

Gravity Probe B is an extremely precise space experiment which will test Einstein's General Theory of Relativity. The cryogenic probe, dewar and spacecraft provide the stable platform and the rigorous environmental conditions necessary for the science instrument to make its demanding measurements. This paper discusses payload and spacecraft technologies developed for Gravity Probe B which also have applicability to future cryogenic space missions. The technologies described include low-magnetic and ultra-high vacuum materials developed for use within the cryogenic probe. Also described are advances in the design of superfluid helium flight dewars including passive orbital disconnect struts (PODS), composite neck tube, honeycomb vapor cooled shields, light-weighted helium tank and vacuum shell, and a guard tank developed to simplify dewar servicing on the launch pad. Additionally, a high stability mount for the attitude gyros and star tracker, a proportional helium thruster for attitude and translation control, a thruster isolation valve, and a mass trim mechanism for precise on-orbit control of the space vehicle lateral center of mass and products of inertia are described.

Verification testing of the superfluid helium on-orbit transfer (SHOOT) experiment

The Superfluid Helium On-Orbit Transfer (SHOOT) project is a secondary shuttle crossbay payload which flew on the STS-57/Endeavour mission. It was designed to develop and demonstrate the technologies required to resupply liquid helium containers in space, and to develop new technologies that may be used in other future space cryogenic systems. The SHOOT payload consists of two superfluid helium Dewars with helium management cryostats connected by a transfer line, and six avionics boxes for valve and heater control, temperature, pressure and fluid position monitoring and data processing and telemetry. The cryostats contain numerous specialized helium management components; including high and low flow phase separators, liquid/vapour discriminators, flowmeters, liquid level detectors, cryogenic mechanical valves and cryogenic relief valves and burst discs, and two varieties of fluid acquisition systems. To prepare the SHOOT payload for launch a series of functional, structural, thermal and reliability tests were conducted at every level of hardware assembly, from materials tests to system level thermal, structural and functional performance tests. We present here the verification tests and analyses developed and completed at each level of assembly. We discuss the trade-offs considered for, and the success (or failure) of, models and analyses to predict performance results. Finally, we present some lessons learned of potential interest to future cryogenic missions, whether on the Space Shuttle or on expendable launch vehicles.